One of the main rebel groups in the Western Sudan Darfur region is calling for the African Union and United Nations to intervene urgently to halt further fighting along the Chad-Sudan border.

The Justice and Equality Movement, one of the two main rebel factions in Darfur, accuses the Sudan government of violating an existing ceasefire by sending troops and weapons to the border with Chad.

Sudan government forces have been deployed along the border to contain raids by Chadian rebel groups based in Sudan.

The leader of the Justice and Equality Movement delegation at the ongoing Abuja peace talks, Ahmed Tugod, says the fighting is having a profound effect on the peace process.

"I think the developments in western Darfur and the borders between Chad and Sudan have grave concerns relating to the whole process, whether inside Sudan or in the peace process here," he said. "As far as the situation in Western Darfur is concerned, the Sudan government harbored a group of Chadian rebels and as a result of this, the presence of Chadian rebels, the Chadian government is also concerned about what is going at the border. This created tension in the area and also gave the Sudan government a chance to bring more troops and weapons in the area. This is a clear violation of the Ndjamena ceasefire agreement."

Tugod is also calling for a quick intervention by the African Union, which has about 7,000 troops in the region, as well as the United Nations.

"We talked two days ago with Jan Pronk, the special representative of the UN secretary general in Sudan about the developments and we asked the African Union to increase their presence in Western Darfur, basically these are areas where there are many camps for refugees and IDPs [internally displaced people]. So it is very important that the African Union has to take steps in order to protect the civilians and also in order to calm down the situation on the ground," noted Tugod. "On the other hand, the United Nations, the security council has to play a major role to curb the situation."

Human Rights Watch says attacks on Chadian villages by militias operating from Darfur could widen the conflict that has killed more than 300,000 people in Sudan.

The New York-based group alleges the Sudan government is complicit in the cross-border raids. The United Nations is expected to send about 20,000 peacekeepers to Darfur to replace over-stretched African Union troops.

The immediate task of the proposed force will be to improve security and humanitarian activities.